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       MASTER FERMENTATION CALCULATOR SPECIFICATION - PART 7: ACID TIER
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A technical backend manual covering cellular population densities, lactic acid
mass titrations, volatile acidity safety limits, and food-safe concentration
metrics mapped directly to standard SI metric base and derived units.
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1. MICROBIAL POPULATION DENSITIES & BIOMASS VIABILITY
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*   Colony Forming Units per Milliliter (CFU/mL)
    - Description: The standard biological unit used to quantify the population density
      of live, active probiotic bacterial cells (Lactobacillus, Acetobacter) and
      fermenting yeasts per unit volume of liquid culture.
    - Core Users: Quality assurance food labs, kombucha brewers, kefir producers,
      and yogurt regulatory compliance teams.
    - Metric / SI Baseline Value: Volumetric particle concentration index.
      Expressed as: 1 CFU/mL = 1,000,000 active cell clusters per cubic meter (10⁶ particles/m³).

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2. ORGANIC ACID TITRATION BALANCES
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*   Titratable Acidity as Lactic Acid (% TA Lactic)
    - Description: Measures the mass concentration of lactic acid in fermented dairy,
      reported as a weight-to-volume percentage fraction. While wine scales prioritize
      tartaric acid and cider uses malic acid, dairy culture backends rely completely
      on a lactic acid baseline molecule.
    - Core Users: Yogurt manufacturers, cheesemakers, and commercial kefir processors.
    - Metric / SI Baseline Value: Mass per volume concentration fraction.
      Expressed as: 1% TA Lactic = 10 grams of pure lactic acid per liter of liquid (10 g/L = 10 kg/m³).

*   Volatile Acidity (VA)
    - Description: Measures the concentration of steam-distillable volatile organic
      acids—primarily Acetic Acid—present in active vinegar and kombucha cultures.
      Tracking VA is legally required to check SCOBY health and ensure a kombucha
      fermentation does not generate unauthorized trace levels of ethanol.
    - Core Users: Kombucha micro-brewers, industrial vinegar picklers, and food scientists.
    - Metric / SI Baseline Value: Mass concentration per volume unit.
      Expressed as: 1 g/L Acetic = 1 kg/m³ (SI Base: kg, m).

*   HIGH-PRECISION CONVERSION FORMULAS FOR ACID INTERSECTION:
    - TA as Lactic (g/L) to Wine Standard Tartaric Equivalent:
        Tartaric Acid (g/L) = Lactic Acid (g/L) * 0.833
    - TA as Tartaric to Dairy Standard Lactic Equivalent:
        Lactic Acid (g/L) = Tartaric Acid (g/L) * 1.200
    - Volatile Acidity to Total Acidity Contribution:
        Acetic Acid (g/L) = Titration Volatility Constant * Volume of NaOH (mL)

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3. SOLID INTEGRITY & DENSITY STABILITY
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*   Total Solids-Not-Fat (SNF %)
    - Description: Measures the mass percentage of dissolved and suspended dairy
      nutrients (proteins, lactose, minerals) remaining in milk after subtracting
      pure butterfat mass. This baseline determines the physical thickness, water-binding
      capacity, and structural gel stability of the target yogurt post-fermentation.
    - Core Users: Dairy engineering plants and cultured food laboratory analysts.
    - Metric / SI Baseline Value: Mass fraction percentage unit. Calculated as:
      (Dry Mass minus Fat Mass in kg / Total Sample Fluid Mass in kg) * 100 (SI Base: kg).

*   Brix-to-Acid Ratio (BAR)
    - Description: A calculated dimensionless sensory and chemical balancing indicator
      found by dividing unfermented substrate sugar density (Brix) by Total Acidity (TA).
    - High-Precision Balanced Equation:
        BAR = °Brix / Total Acidity (g/L)
    - Metric / SI Baseline Value: Dimensionless architectural indexing ratio.
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